convert usage of fail* to assert*
diff --git a/Lib/test/test_StringIO.py b/Lib/test/test_StringIO.py
index 58cbec0..f5a177e 100644
--- a/Lib/test/test_StringIO.py
+++ b/Lib/test/test_StringIO.py
@@ -85,7 +85,7 @@
 
     def test_iterator(self):
         eq = self.assertEqual
-        unless = self.failUnless
+        unless = self.assertTrue
         eq(iter(self._fp), self._fp)
         # Does this object support the iteration protocol?
         unless(hasattr(self._fp, '__iter__'))